Ethernet Backbone in Car: Hype or Reality?

However, Ian Riches, director of global automotive practice at Strategy Analysis, told EE Times, "Our current estimates are that in 2020 around 120 million Ethernet nodes will be fitted to light vehicles produced that year."

When asked how many Ethernet nodes are expected in a high-end car in 2020, Riches said, "I would be surprised if it hit 100 Ethernet nodes."

He counted up to five domain controllers on the backbone (powertrain, safety, chassis, body, infotainment), 10 to 20 infotainment nodes, 10 to 15 nodes for advanced safety, 1 node for diagnostics, and 10 to 20 additional nodes for other high-end features.

The big gap in forecasts could be partly explained by differences in expectations of how fast the ECU in the vehicle goes Ethernet.

Frost & Sullivan's Chandrasekar believes in the idea of a backbone network supporting other networks. But he made it very clear that "the backbone would be Ethernet-driven. The CAN, MOST, LIN and others will continue to exist on a small scale basis, but Ethernet will drive the majority of the work."

In Riches's opinion, "Not every function in the vehicle requires the 100Mbps-plus" offered by automotive Ethernet. A seat control motor, for example, won't gain extra functionality from being on an Ethernet network rather than the low-speed CAN or local interconnect network (LIN) that runs it today, explained Riches. "Unless Ethernet is cheaper than LIN, then LIN at the very least will remain for many low-end functions." He added that part of the backbone/domain controller architecture trend leans toward reducing the number of ECUs in the vehicle -- which means fewer Ethernet nodes than in Frost & Sullivan's forecast.

Tipping point
Luca De Ambroggi, senior analyst, IHS's Automotive Component and Device Electronics and Media, is more cautious about the rate of Ethernet adoption. He thinks Ethernet is still looking for a place to break through. "I believe this breakthrough point is infotainment, followed by basic ADAS application like Camera based functions," he said.

Obviously, for automotive Ethernet to succeed, "The target of Ethernet must be the entire auto wiring system from Infotainment down to the most safety and security critical segments like body." Nonetheless, De Ambroggi believes "Ethernet needs a small step approach to be mature and bullet-proof for automotive."

As Broadcom likes to point out, there is a definite upside in using Ethernet in a car -- in terms of savings in cost and weight.

Single-pair Automotive Ethernet, which uses un-shielded twisted pair (UTP) cable to deliver data at a rate of 100Mbps, along with smaller and more compact connectors “can reduce connectivity cost up to 80 percent and cabling weight up to 30 percent,” according to Broadcom.

While acknowledging potential savings, Strategy Analysis's Riches pointed out, "There are also significant risks when adopting a new technology."

For one, there is always a cost-to-change. At this stage, the additional costs are arguably easier to quantify than any potential savings, he said. While an Ethernet backbone would be an enabler for greater functionality in the vehicle, he also noted, "Whether that functionality will be required (or affordable) on a mass-market 2020 vehicle is far from certain."

In summary, Riches noted that there's a theoretical tipping point where the number of features and bandwidth required will be cheaper to "start again" with an Ethernet backbone-type architecture. "But I don't see us as being there before 2020 at the earliest for volume car makers,” he said.

Also, Automotive Ethernet uses a signaling scheme with higher spectral efficiency compared to the signaling scheme used in 100BASE-TX, according to Broadcom. This limits the signal bandwidth of Automotive Ethernet to 33.3MHz, which is about half the bandwidth of 100BASE-TX. As a result, "a lower signal bandwidth improves return loss, reduces crosstalk, and ensures that Automotive Ethernet passes the stringent automotive electromagnetic emission requirement," the company said.

Strategy Analysis's Riches, however, believes that some technical questions still remain. "I still hear concerns over EMC performance for Ethernet over UTP." Riches, however, quickly added that "how much of this is real as opposed to just fear-of-the-unknown is hard for me to judge."

Other criticism questions whether the current 100 Mbps of BroadR-Reach might be too slow, Riches added. "It essentially means that camera images will need to be compressed -- which some see as a big problem for safety systems."

There are players that seem to be waiting for Gbps in automotive, said Riches. "Moves are underway at IEEE level to standardize this -- but these things take time."

While you are at it you might want to see what technology they are planning on using. Switched Ethernet is pretty much all that is being used today, but shared backbone media might significantly simplify the wiring. At a minimum I could see multiple localized switches. You are not going to want 100 ports on a single switch!

100 year old "Early American antique" cars grace our highways from time to time; will it be possible to maintain the current generation of cars in a century?

DrQuine, I haven't even thought about it before...but it's true. With all these complexity (and not to mention, "islands" of different proprietary nteworking technologies proliferated in cars over time), we may never see cars today being trotted out on highways 100 years from now!

The obligation of auto manufacturers to maintain spares and repair capabilities for vehicles during their likely lifetime gets much complex with yearly changes in networking systems. By the time security upgrades are included (the dozens that Microsoft feels compelled to provide to my computer), the configuration control for a car will become an absolute nightmare. I think it is time to standardize and simplify. 100 year old "Early American antique" cars grace our highways from time to time; will it be possible to maintain the current generation of cars in a century?

There are a couple questions we need to ask ourselves prior to putting Ethernet in a car.

1) How many devices needs to be connected?

2) Do the devices need to talk to each other?

3) Do the existing techologies serve the purpose?

4) How is the wiring done?

5) Where is the Ethernet Switch going to be?

There is an advantage of direct connectivity - 1 fewer device; 1 less uncertainity. Who wants to see a blinking dashboard when the Ethernet switch goes down?

I agree Infotainment is one of the key drivers to the wired automobile. Nowaday, kids are enjoying their cartoon shows and browsing their social network sites in the backseat with their connected tablet. Does Ethernet wired automobile add value to the Infotainment push?

On the other hands, if Ethernet wired automobile is demanded, I believe BroadR-Reach is a superior technology to the job. I learned about the technology in a couple years ago that it can serve with 2 wires (twisted or parallel). The fact that it has high noise rejection ability will definitely fit the environment of any vehicles.

@amagnani, your points are well taken. Actually such efforts as brining in Wi-Fi to wirelessly connect consumer devices (brought into a car) with a backseat display, for example, are already happening.

But carmakers do have immediate needs for a bigger bandwidth networking technology, for example, to accomodate more than several cameras already installed inside a car for driver assistance. These embedded vision cameras will be streaming video in parallel in real time. LVDS won't cut it.

When you look at designs of future cars, you need to consider networking technologies that can scale. That's I think where Ethernet comes in.

The comments to this article thus far point towards two areas which are important: the physical layer (PHY, cables, etc.) and the higher level protocol (software) layers that ride on top of Ethernet. The part in the middle ("Ethernet") is not being affected.

The automotive industry identified several challenges that need to be overcome to make the whole system be suitable for automotive applications. On the physical layer are discussions ongoing on the required bandwidth and speed, resulting in discussions about both 100 Mbit/s and 1 Gbit/s. And which existing or new PHY solutions could support these communication speeds and meet the automotive EMC, power consumption and cost requirements at the same time. OPEN SIG, IEEE RTPGE and JASPAR are just three examples of consortia that focus on this aspect. For the higher level software is also discussion ongoing about topics like AVB, TSN (Time Sensitive Networks) and profiles. Involved consortia are for example AVnu, AUTOSAR, JASPAR.

All in all enough hurdles that need to be overcome to justify the careful remarks of some of the people who were interviewed in the article.

At least such isolation will prevent the car hackers from taking control of the Car . A CAN network will control the vital systems of the Car such as ECU, braking etc and these systems can remain out of reach for the hackers.